Fundus imaging is the essential diagnostic procedure in ophthalmology. Instruments of the prior art that are useful for examining the fundus of the eye include direct and indirect ophthalmoscopes, the slit-lamp biomicroscope and the fundus camera. Complementary tools have been developed that broaden diagnostic and therapeutic possibilities, such as the Scanning Laser Ophthalmoscope (SLO). The SLO is a superior tool for rapidly and continuously acquiring high-contrast images of the ocular fundus and its structures, including the distribution of choroidal blood, melanin, and retinal pigments. Because it accommodates a variety of visible and NIR wavelengths, the SLO is especially useful for the study and early diagnosis of diseases such as age-related macular degeneration (AMD) and diabetic retinopathy. These are the leading causes of blindness in the elderly. The SLO is a powerful diagnostic tool for characterizing retinal pathologies, as well as for angiography, tomography, perimetry, and general psychophysics. Confocal SLO imaging is very effective in patients suffering from mild cataract, or from pathologies causing clouding of the vitreous. Another device for examining the fundus of the eye is the instrument described in U.S. Pat. No. 6,267,477, issued on Jul. 31, 2001 to Karpol et al. The Karpol instrument is described as operating on the principle of slit lamp bimicroscopy performed on an eye having a dilated pupil. The Karpol instrument uses a defined angle between a beam going to the retina and a beam returning from the retina, and there is a distance at the area of the pupil between the incident beam and the measured scattered beams. The Karpol instrument uses a two dimensional CCD camera as one of three cameras used to record images.
However, although they have become valuable diagnostic tools in the research community, scanning laser devices have not yet emerged into widespread clinical usage, due in part to their size, cost, and complexity. As a result, they are usually found only at specialized facilities, are used almost exclusively by ophthalmologists, and are often unavailable when needed. In particular, elderly and emergency patients are often unwilling or unable to travel to a specialized clinic for testing. But even the ubiquity of slit-lamps, fundus cameras and indirect ophthalmoscopes does not necessarily allow their use in many circumstances in which they may be indicated, such as emergency care. These devices may not be immediately accessible, and in many circumstances, the primary care physician may not choose to use instruments like Binocular Indirect Ophthalmoscopes (BIO's) which are more difficult to master, and may be unpleasant for the patient. The fallback device is the direct ophthalmoscope. The availability of hand-held and tele-ophthalmoscopic fundus imaging systems of the standard types are increasing, but their cost remains high, and they continue to have the limitations discussed. A portable, convenient, and less expensive system that provides high quality images of the fundus has been lacking.